Pulmonary arterial hypertension (PAH) is a disorder characterized by high blood pressure in the arteries of the lungs. PAH is one of the five classes of pulmonary hypertension (PH). The other four types of PH are venous, hypoxic, thromboembolic and miscellaneous PH. PAH is a condition in which the progressive obliteration of the pulmonary vasculature leads to increased resistance to blood flow through the lungs. In turn, this obstruction leads to right heart failure and, ultimately, death. PAH mainly affects young and middle-aged women.
Current methods of treating PAH focus on prolonging patient lifespan and enhancing patient quality of life. Such methods include administration of: vasodilators such as prostacyclin, epoprostenol, and sildenafil; endothelin receptor antagonists such as bosentan; calcium channel blockers such as amlodipine, diltiazem, and nifedipine; anticoagulants such as warfarin; supplemental oxygen therapy and diuretics. When medical treatment fails, the final therapeutic option is lung and/or heart-lung transplantation. Each of these methods, however, suffers from one or multiple drawbacks such as lack of effectiveness, serious side effects, low patient compliance, and high cost.
Accordingly, new compounds, compositions of those compounds in the form of pharmaceutical formulations, medicaments containing those formulations and unit dose forms of them, and methods for treating PAH are needed. The present invention addresses these needs.